Portable psychrometer



`Fuly 19, 1927.

J. ARMSTRONG PORTABLE PSYCHRQMETER Filed Aug. 51 '1926 2 SheetsSheet L.U0 KUL Jul 19 1927.

y J. ARMSTRONG PORTABLE PSYCHROMETER Filed Aug. 1,51 1926 2 Sheets-Sheet2 IN VEN TOR l ll lul 0 ff/vi( Patented July. 19,. 1927.

UNITED STATES 1,636,350 PATENT-'b' OFFICE.

JOSEPH ARMSTRONG, l' ALLSTON, MASSACHUSETTS, ASSGNOB T0 AMERICAN MOTS-TENING COMPANY, 0F BOSTON, MASSACHUSETTS, A CORPORATION 0F MAINE.

PORTABLE PSYCHBOMETER.

Application led August 31, 1928. Serial No. 132,688.

This invention relates to improvements 1 n portable psychrometers. Moreespecially. 1t relates to instruments of this sort 1n wh1ch a fan isemployed to drive a blast of air past I the thermometer bulbs and has todo particularly with the provision of manually actuated mechanism forrotating the tan.

In the working of fibrous materralstsuch as cotton and wool for example,it 1s hlghly 1'0 important that the air coming 1n contact with thesematerials be tempered with the proper amount of entrained moisture. Hu-

midifying apparatus is avallable for supplying this moisture and controldevlces have been developed for regulating their moisture discharge inaccordance with the air conditions existing at the location of thecontrol units. The latter, however, are usually mounted in some centralor average l0 location in a room where there 1s a convenient support andit is not unusual to find that the air conditions there are not the sameas those of the region closely ad]acent to the material being worked. Itis accordingly desirable to test the air condltlons at various locationsmore or less remote from the lcontrol devices and in greater proximityto the material itself. The present invention is directed to theprovision of a psychrometer which can be carried in hand to anylocation, and there held stationary while a continuous blastv of the airbeing tested 1s driven past the wet anddry bulbs of its thermometers.

provide a simple compact device in which there is a fan for moving theair past the bulbs and mechanism by which the power of the testers thumbor finger is utilized to o effect rotation of the fan. It is a featureof the device that when the wet and dry bulb temperatures have beendetermined the percentagesof relative humidity and cotton or vwoolregain, corresponding to those temperatures, can be readily ascertainedfrom an integrating device mounted on the instrument. v

These objects are attained byv mounting a pair of thermometers at thefront of a vertically extending casing which rises from a hollow basethat serves as a reservoir for water. The latter is carried to the bulbof one of the thermometers by a wicking encasing the bulb. A rotatablefan is set within the casing in position to blow apsample of air vWhenthus set, the percentages of cotton It is an object of the presentinvention tol uniformly past both the wet and dry bulbs. The casing hasan external handle at the rear by which the instrument can be su portedin one hand, and close by the han e is a rod which can be pusheddownward by the thumb or a finger of that hand. This rod is part ofpower transmission mechanism whereby the linear motion imparted to therod is transformed into rotary motion of the fan. A ratchet mechanismpermits a spring to return the rod to starting position ready foranother push downward by the operator while the momentum ofthe fancontinues it in motion. Thus a sample of air is caused to blow uniformlypast both thermometer bulbs, gradually lowering the temperature of thewet bulb thermometer in accordance with the amount of moisture thepassing air is able to take up from .the wicking.

- On the front of the casing, between the thermometers, is anintegrating device having a movable element which can be Set inaccordance with the wet and dry bulb temperature readings of thethermometers.

regain, relative humidity and wool regain corresponding to the saidtemperatures will be indicated simultaneously by the device.

It is intended that the patent shall cover by suitable expression in theappended claims whatever features of patentable novelty exist in theinvention disclosed.

In t e accompanying drawings:

y Figure 1 is a front elevation of aportable psychrometer embodying thepresent invention;

Figure 2 is a side elevation, in medial section on line 2--2 of Figure1;

Figure 3 is a plan, on line 3 3 of Figure 2, but with most of the basecut away;

Figure 4 is an elevation on line 4:-4 of Figure 2, of the lower end ofthe push rod and connected gearing;

Figure 5 is an elevation like Fi re 4, but on line 5-5 of Figure 2,showing the mechanism as seen from the front; and

Figure 6 is a rear view of the instrument.

Referring to the drawings, a casing 10 has a hollow base 12 holding asupply of 105 Water which may be poured into it through an openingnormally closed by screw cap 16. Two thermometers 18 and 20, one forregistering the dry bulb temperature and the other for registering wetbulb tempera- 110 ture, are mounted in ves formed by side strips and 10"astened to the front edges of the side walls 10. The bulb of eachthermometer extends below its supportin strip to near the bottom of thecas in be 'nd a rforated cover plate 22. The bu b of tiig wetthermometer is encased within a wick 26 which extends into the reservoirbase 12 and by capillary action feeds moisture to the region of the bulbwhere it is evaporated by the air around it. This air in the immediatevicinity of the wet bulb soon becomes more or less saturated and cannotthen absorb moisture as fast as would the air further removed from thebulb; in fact the entire air within the casing becomes slightlymoistened and as a result the dry bulb thermometer actually reads lowerthan the tem erature of the air outside the casin and t e wet bulbthermometer reading is higher than that showing true wet bulbdepression. In order to insure accurate readin of the two thermometersthere is rovided a fan 28 set to draw outside air t rough an opening 29in the back of the casing, and blow it uniformly across both bulbs andout through the perforations 24 in the front cover plate. Thus acontinuous stream of the air to be tested affects both thermometers,causing the dry bulb instrument to show the actual temperatures of theairand the other thermometer to show the ltemperature corresponding tothe wet bulb depression for that air. The latter is of course dependentupon the actual humidity in the air and the amount of moisture that canbe absorbed from the wick.

A handle 30 is provided on the back of the casing by which thepychrometer can be held in the hand at any esired location. The upperend 30 of'this handle ro'ects through an upper openin 32 in t e. ackwall and forms a bearing or a rod 34 which has a button 34 on its upperend in position to be pressed conveniently by the operators thumb orfinger. The lower end of this rod is forked and straddles a raised striwhich is pressed outward from a di 38 and serves to guide the rod in itslinear travel. The disk is mounted on a depending plate 40 attached tothe casing by the same means 42 that clam s the lower end of the handlethereto, and is thus positioned centrally of the opening 29.

On the raised guide strip 36 is secured a small plate 46 which overliesthe forked prongs 34" of the push rod and keeps the latter from movingaway from the ,face of the disk. A spring 48 anchored to this plate andattached to one of the prongs serves to pull the rod upward when thepressure of the thumb is released at the end of a down stroke. Theoutside e' of one of the prongs 34" is provided with teeth and thusconstitutes a rack which meshes with a small pinion 50 supported on ashaft 52 having one bearing in the disk 38 and the other iii a bracket54 mounted on one edge of the disk with its arm 54 extendin across it.On this shaft 52, and secured the small pinion 50, is a ratchet wheel 54whose teeth are cut with a driving face on one side and a cam face onthe other. A larger gear 56 is also journaled on the shaft 52 beside thewheel 54 and carries on its side a pivoted pawl 58 which is ii1 the laneof the ratchet wheel. When the latter is rotated in one direction bydownward thrust of the ush rod, the driving face of one of its ratc etteeth engages the pawl and causes the large gear to turn with it, andsince the latter meshes with a small gear 60, fast on the fan shaft 62,the fan is also rotated. When .the rod 34 is moved upward by the sprin48, the cam faces of the ratchet wheel teet slide freely by the pawl,allowing the fan to continue to rotate under its momentum. Before itcomes to rest another downward stroke of the push rod occurs and thusthe fan is kept continuously in rotation by the operator succeivelypushing the ro'd downward as it is returned by the spring.

The psychrometer can be carried to any location where a test is desired,and by simply pushing down on the rod, as explained, a continuous streamof air can be passed simultaneousl over both the wet and dry bulbs. Atfirst their readings will chan e, the dry temperature slightl rising andt e wet tem erature falling. en the mercu in oth thermometers standsstill the rea ing of each is taken and, by means of an integratingdevice mounted on the instrument, the percentages of relative humiditand cotton 4or wool regain can be quickly determined. y This devicecomprises a scale plate 64 arranged on the front of the casing betweenthe grooved strips 10 and 10". This late has turned over edges which liebehind) the inner edges of the grooved strips and form ides for a slidinelement 66. A slot 64 1s cut centrally of t e scale plate and on one ofits edges is laid out raduations 682 from 50 to 110 for examp e,corresponding to the graduations of the wet bulb thermometer. On theslidin element 66, ad'acent the graduations 68 and visible through theslot 64l are similar graduations 70 laid out to represent the degrees ofthe dry bulb thermometer. On the other edge of the slot 64 are threesets of graduations, one` 72 representing percentages of cotton regain,another 74 representing percentages of relative humidity, and the third76 representing Vpercentages of wool regain. In proper relation to thesethree sets of graduations on the xed scale plate are three arrows orindicators 78 on the sliding element.

y los 1,ese,aso

When the readings of the thermometersulb temperature is set opposite thegraduation of the fixed wetbulb scale which corresponds to the wet bulbtemperature. The percentages of cotton regain, of relative humidity andof wool regain, corresponding to the temperature readings, are thenindicated simultaneously b the three` arrows 78 on the respective sca es72, 74 an'd 76. I

lThe convenience of the psychrometer is obvious. It can be used anywherethat a hand can hold it. It is not dependent upon a source of ower otherthan the operators muscular e orts. And because it employs no otherpower mea-ns, as for example an electric motor, thereis no danger of thelead wires becomin entangled in the fibrous material and no re hazardfrom the sparks of such a motor. The'device is sim e, can bemanufactured at small cost, and 1s accurate in operation.` It determinesthe dry and wet bulb temperatures and enables the tester to 'ascertainfrom these the 'desired characteristics of the air being tested.

I claim as my invention:

1. A psychrometer comprising, in combination, a casing havin a reservoirfor water in its base; a pair of t ermometers mounted on the front Wallof said casing; a wick extending from said reservoir aroundvone of thethermometer bulbs; a fan arrangedin said casing for blowing air to betested past both bulbs; a handle on the back of said casing -whereby thepsychnometer can.l be

held in the hand; a ush rod arranged with respect to said handle toenable the rod to be actuated by the hand holding the psychrometer; andpower transmitting connections between Isaid rod `and the `fan for`transforming the linear movement of said rod into rotative movement ofthe fan.

v2. A psychrometer comprising, in'combination, a casinoP having a pairofI thermometers mounted th moisture to the bulb of one thermometer ltobe evaporated therefrom; a fan arranged within said casing for blowingair to be tested past the thermometer bulbs; means for holding saidcasing in the hand;v a'nd power ereon; means for supplying transmissionmeans having operative connection with the fan and adapted to receivepowerA impulses from the hand and transmit them to the fan, comprising arod adapted to be engaged by the hand and having teeth along its edge, atrain of gearing meshing with the teeth on said rod and adapted to causerotation of said fan.

3. A psychrometer comprisin in combination, a casing having a pairothermometers mounted thereon; means for affecting said' thermometerswhereby they will show respectively wet and dry bulb temperatures; andmeans on said casing interposed between said thermometers comprising ascale plate having graduations corresponding to the graduations on oneof said thermometers and othergraduations laid out in relation theretocorresponding to percentages of the c1` acteristic property of the airto be determined; another scale movable with respect to said scale platehaving graduations thereon arranged in accordance with the graduationsof the other of said thermometers and having an indicator arranged toindicate on the percentagey raduations the characteristic property of te air when said thermometerscales are positioned with their graduationscorresponding to their respective thermometer readings opposite to oneanother.

-4. In apparatus for registering wet and dry bulb temperatures, thecombination with the thermometers thereof of integrating meansconsisting of four stationary scales with graduations corresponding towet bulb temperatures, cotton regain, relative humidity, and Wool regainpercentages respectively, and a sliding scale with indicationscorresponding to dry bulb temperatures and adapted to be moved relativeto the stationa scales; there being three ointers on said slidable scaleadapted to in lcate conditions of the air on said percentage scales whenthe graduation on the slidin scale cor- `responding to the existing drybul temperature is made to register with the graduation on the Wetbulb'stationary scale corresponding to the existing wet bulbtemperature.

Signed at Boston, Massachusetts, this 25 day of August, 1926. JOSEPHARMSTRONG.-

